A stent is a structure which is designed to maintain the patency of a bodily vessel. Stents are delivered to a desired bodily location in an unexpanded configuration having a reduced cross-section and expanded to a configuration having an increased cross-section. Stents are typically self-expandable or mechanically expandable. Examples of self-expandable and mechanically expandable stents are disclosed in WO 9626689 and U.S. Pat. No. 6,042,597.
It is desirable for a stent to be flexible in the unexpanded configuration to facilitate delivery of the stent through tortuous vessels and to have a sufficient degree of rigidity in the expanded configuration to support a vessel. It is also desirable for a stent in the expanded configuration to provide sufficient vessel coverage.
Although a vast number of stent designs have been disclosed in recent years, there remains a need for innovative stent designs which are flexible in the unexpanded configuration and which exhibit improved coverage characteristics in the expanded configuration. There also remains a need for stents with improved expansion ratios relative to current stents.
All U.S. patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
The invention in various of its embodiment is summarized below. Additional details of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
In one embodiment, the invention is directed to a stent comprising at least one band of interconnected cells selected from the group consisting of circumferentially oriented S-shaped cells and circumferentially oriented mirror image S-shaped cells. Each cell has a top end and a bottom end. The top end of each cell is attached to the bottom end of an adjacent cell in the band. The stent may comprise a plurality of interconnected bands of interconnected S-shaped cells and/or mirror image S-shaped cells. Where bands of S-shaped cells and bands of mirror image S-shaped cells are present, the bands may alternate over the length of the stent or be provided in any other suitable arrangement. Adjacent bands of S-shaped cells and/or mirror image S-shaped cells may abut one another or may be joined by connecting members. Where connecting members are provided, the members may be straight or may have one or more bends therein. The stent may have a single type of connecting member or multiple types of connecting members. Adjacent connecting members may be joined to one another to form differently shaped cells. In one embodiment, the differently shaped cells are generally arrow shaped.
The invention is also directed to a stent comprising at least one cell selected from the group consisting of S-shaped cells and mirror image S-shaped cells.
The invention is also directed to stents comprising at least one band formed of a plurality of substantially X-shaped members. Each X-shaped member has a proximal end and a distal end and includes a first arm of a first length, a second arm of a second length different from the first length, a third arm of a third length and a fourth arm of a fourth length different from the third length. The first and second arms extend in a distal direction and the third and fourth arms extend in a proximal direction. Adjacent X-shaped members are joined together at the distal end by a first loop member extending there between and at the proximal end by a second loop member extending therebetween. The first loop member and the second loop are non-parallel to the longitudinal axis of the stent. The first loop member includes a first loop oriented substantially in the proximal direction and a second loop oriented substantially in the distal direction and the second loop member includes a first loop oriented substantially in the proximal direction and a second loop oriented substantially in the distal direction. Adjacent bands of substantially X-shaped members may abut one another or may be joined by connecting members extending therebetween. Where connecting members are provided, the members may be straight or may have one or more bends therein. The stent may have a single type of connecting member or multiple types of connecting members. Adjacent connecting members may be joined to one another to form differently shaped cells. In one embodiment, the differently shaped cells are generally arrow shaped.
The invention is also directed to a stent comprising one or more cells with each cell consisting of two inwardly pointing fingers, one of which opens in a proximal direction and the other of which opens in a distal direction. The closed portion of the finger which opens in the distal direction is located proximal of the closed portion of the finger which opens in the distal direction.